feat(02-03): wire main.rs with highlighter init, vault loading, and renderer

- Add highlighter::init_highlighter() call before render_markdown()
- Load index.md via vault::load_document() with proper VaultDocument matching
- Query terminal size before terminal init for initial render width
- Render markdown via renderer::render_markdown() passing content and width
- Pass raw content string to App::new() for resize re-rendering
- Update App::new() call with all 4 arguments (is_login_shell, config, doc, raw)
- All 7 modules declared: app, config, highlighter, renderer, signals, terminal, vault

src/main.rs

@@ -27,6 +27,35 @@ fn main() {
         }
     };
 
+    // 3a. Initialize syntax highlighting (one-time, loads embedded syntax definitions)
+    //     Must be called before render_markdown() — highlighter uses OnceLock statics.
+    highlighter::init_highlighter();
+
+    // 3b. Load initial document (index.md from vault) and render it.
+    //     We query the terminal size here for initial render width.
+    //     On resize, the event loop re-renders with the updated width.
+    let initial_width = ratatui::crossterm::terminal::size()
+        .map(|(w, _)| w)
+        .unwrap_or(80);
+
+    let (initial_doc, raw_content) = match vault::load_document(&app_config.vault_path, "index.md") {
+        vault::VaultDocument::Loaded { path, content } => {
+            let filename = path
+                .file_name()
+                .map(|n| n.to_string_lossy().to_string())
+                .unwrap_or_else(|| "index.md".to_string());
+            let lines = renderer::render_markdown(&content, initial_width);
+            let doc = app::DocumentState::Loaded { filename, lines };
+            (doc, Some(content))
+        }
+        vault::VaultDocument::Missing { path } => {
+            (app::DocumentState::Missing { path }, None)
+        }
+        vault::VaultDocument::ReadError { path, reason } => {
+            (app::DocumentState::Error { path, reason }, None)
+        }
+    };
+
     // ── TERMINAL PHASE ────────────────────────────────────────────────────────
     // Install safety envelope BEFORE terminal init so panics during init are caught.
 
@@ -54,9 +83,9 @@ fn main() {
 
     // ── EVENT LOOP PHASE ──────────────────────────────────────────────────────
 
-    // 7. Create app state and run the event loop
-    //    app_config is stored in App for Phase 2+ use (vault_path, theme).
-    let mut app_state = app::App::new(is_login_shell, app_config);
+    // 7. Create app state and run the event loop.
+    //    raw_content is passed so the event loop can re-render on terminal resize.
+    let mut app_state = app::App::new(is_login_shell, app_config, initial_doc, raw_content);
     let shutdown_reason = app_state.run_event_loop(&mut term, &signal_flags);
 
     // ── SHUTDOWN PHASE ────────────────────────────────────────────────────────